El Tue, Dec 04, 2007 at 11:09:02AM -0800 Daniel Walker ha dit:
> On Tue, 2007-12-04 at 17:55 +0100, Matthias Kaehlcke wrote:
> > @@ -1990,7 +1991,7 @@ static void usbtest_disconnect (struct
> > usb_interface *intf)
> > {
> > struct usbtest_dev *dev = usb_get_intfdata (intf);
> >
> > - down (&dev->sem);
> > + mutex_lock(&dev->lock);
> >
> > usb_set_intfdata (intf, NULL);
> > dev_dbg (&intf->dev, "disconnect\n");
>
> This looks like a bit of an anomaly.. The code that isn't shown above is
> the "kfree(dev)" .. So this isn't legal since it's freeing a locked
> mutex. Here's a excerpt from the comment above mutex_lock(),
>
> * The mutex must later on be released by the same task that
> * acquired it. Recursive locking is not allowed. The task
> * may not exit without first unlocking the mutex. Also, kernel
> * memory where the mutex resides mutex must not be freed with
> * the mutex still locked. The mutex must first be initialized
> * (or statically defined) before it can be locked. memset()-ing
> * the mutex to 0 is not allowed.
you're absolutely right that freeing a locked mutex isn't a good idea
thanks for pointing it out!
--
Matthias Kaehlcke
Linux System Developer
Barcelona
Don't walk behind me, I may not lead
Don't walk in front of me, I may not follow
Just walk beside me and be my friend
(Albert Camus)
.''`.
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